Using ordered locking mechanisms to maintain sequences of items such as packets

ABSTRACT

Sequences of items may be maintained using ordered locks. These items may correspond to anything, but using ordered locks to maintain sequences of packets may be particularly useful. One implementation uses a locking request, acceptance, and release protocol. One implementation associates instructions with locking requests such that when a lock is acquired, the locking mechanism executes or causes to be executed the associated instructions as an acceptance request of the lock is implied by the association of instructions (or may be explicitly requested). In some applications, the ordering of the entire sequence of packets is not required to be preserved, but rather only among certain sub-sequences of the entire sequence of items, which can be accomplished by converting an initial root ordered lock (maintaining the sequence of the entire stream of items) to various other locks (each maintaining a sequence of different sub-streams of items).

TECHNICAL FIELD

One embodiment of the invention relates to communications and computersystems, especially routers, packet switching systems, and otherdevices; and more particularly, one embodiment relates to using orderedlocking mechanisms to maintain sequences of items which may includeconverting between ordered locking mechanisms.

BACKGROUND

The communications industry is rapidly changing to adjust to emergingtechnologies and ever increasing customer demand. This customer demandfor new applications and increased performance of existing applicationsis driving communications network and system providers to employnetworks and systems having greater speed and capacity (e.g., greaterbandwidth). In trying to achieve these goals, a common approach taken bymany communications providers is to use packet switching technology.Increasingly, public and private communications networks are being builtand expanded using various packet technologies, such as InternetProtocol (IP).

A network device, such as a switch or router, typically receives,processes, and forwards or discards a packet based on one or morecriteria, including the type of protocol used by the packet, addressesof the packet (e.g., source, destination, group), and type or quality ofservice requested. Additionally, one or more security operations aretypically performed on each packet. But before these operations can beperformed, a packet classification operation must typically be performedon the packet.

These operations consume time and resources, so one way to speed uptheir performance is to use multiple processors and to process packetsin parallel. However, certain packets belonging to a stream of packetsmay need to be forwarded from the packet processors or even processed inthe order received. Moreover, maintaining the original sequence ofpackets is in conflict with the desire to retire packets from aprocessor as soon as they are done in order to clear resources toprocess more packets. Desired is a way of preserving only the criticalorder of flows, such as, but not limited to that which does not imposearbitrary and non-optimal order between unrelated packets.

SUMMARY

Disclosed are, inter alia, methods, apparatus, data structures,computer-readable medium, mechanisms, and means for using orderedlocking mechanisms to maintain sequences of items which may includeconverting between ordered locking mechanisms. These items maycorrespond to anything, including, but not limited to packets, dataitems, processes, threads, etc.

The number of locks employed by an embodiment may vary and typically iscommiserate with the needs of the application. Locks can be used tomaintain strong ordering of a stream of items. Additionally, locks canbe used to induce ordering of items. For example, a lock can beconverted to multiple different locks which allows the same order to bemaintained within the different locks, while allowing the items of thedifferent locks to be processed in any order, such as, but not limitedto being processed in parallel. Similarly, multiple locks can beconverted to a single lock which induces ordering among items previouslyin the different locks (e.g., typically with the ordering being that inwhich locking requests are processed).

Additionally, certain embodiments may provide for the locking mechanismto perform atomic operations, which are inherent or explicitlyassociated with a locking item. Examples of such atomic actions include,but are not limited to conversion of locks, sequence number generationand/or checking, memory operations, data manipulation operations, etc.In one embodiment, a set or command queue of instructions or otherindications corresponding to the atomic operations to be performed areassociated with a locking item. By allowing the locking mechanism toperform or cause to be performed these operations, the critical latencycan typically be reduced as these operations typically can be pipelinedand localized, rather than distributed. For example, in one embodiment,such an operation is performed by the locking mechanism or a processingelement associated with the locking mechanism, and thus, the delay ofthe communication between the locking mechanism and the lock requestorbefore the operation is performed is typically reduced or eliminated.

One embodiment identifies a particular item, and in response, generatesa locking request to an ordered lock. The ordered lock is configured tomaintain a locking queue of identifiers corresponding to lockingrequests in the order requested. One or more instructions are associatedwith the particular identifier, and when the particular identifierreaches the head of the locking queue, the one or more instructions areperformed.

One embodiment repeatedly identifies a particular packet, and inresponse, generates a locking request to an ordered lock, wherein theordered lock maintains a locking queue of identifiers corresponding thelocking requests in the order requested. Acceptances requestscorresponding to packets are communicated to the ordered lock. Theordered lock repeatedly removes a particular identifier from the head ofthe locking queue, and grants a locking acceptance request correspondingto the particular identifier if a corresponding acceptance request waspreviously generated, or waits until the locking acceptance requestcorresponding to the particular identifier is generated and thengranting the locking acceptance request corresponding to the particularidentifier.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended claims set forth the features of the invention withparticularity. The invention, together with its advantages, may be bestunderstood from the following detailed description taken in conjunctionwith the accompanying drawings of which:

FIG. 1A is a block diagram of an exemplary system employing oneembodiment;

FIG. 1B is a block diagram of a system or component thereof, such as,but not limited to a packet processor, lock mechanism, lock manager,distributor, gatherer, or resource used in one embodiment;

FIGS. 2A-2C illustrate an ordered lock used in one embodiment;

FIGS. 3A-3D illustrate an ordered lock used in one embodiment;

FIGS. 4A-D illustrate the concept of a lock conversion used in oneembodiment;

FIGS. 5A-D are a flow diagrams illustrating some of an unlimited numberof embodiments for using ordered locks to maintain sequences of packets;

FIG. 6A is a block diagram of an exemplary system using ordered locks tomaintain sequences of packets; and

FIG. 6B is a flow diagram illustrating a process using ordered locksprocessing using ordered locks to maintain sequences of packets.

DETAILED DESCRIPTION

Disclosed are, inter alia, methods, apparatus, data structures,computer-readable medium, mechanisms, and means for using orderedlocking mechanisms to maintain sequences of items which may includeconverting between ordered locking mechanisms. These items may beanything, including, but not limited to packets and in which case, usingordered locks to maintain sequences of packets may be of particular usein routers, packet switching systems, and other devices.

Embodiments described herein include various elements and limitations,with no one element or limitation contemplated as being a criticalelement or limitation. Each of the claims individually recites an aspectof the invention in its entirety. Moreover, some embodiments describedmay include, but are not limited to, inter alia, systems, networks,integrated circuit chips, embedded processors, ASICs, methods, andcomputer-readable medium containing instructions. One or multiplesystems, devices, components, etc. may comprise one or more embodiments,which may include some elements or limitations of a claim beingperformed by the same or different systems, devices, components, etc.The embodiments described hereinafter embody various aspects andconfigurations within the scope and spirit of the invention, with thefigures illustrating exemplary and non-limiting configurations.

As used herein, the term “packet” refers to packets of all types or anyother units of information or data, including, but not limited to, fixedlength cells and variable length packets, each of which may or may notbe divisible into smaller packets or cells. The term “packet” as usedherein also refers to both the packet itself or a packet indication,such as, but not limited to all or part of a packet or packet header, adata structure value, pointer or index, or any other part or direct orindirect identification of a packet or information associated therewith.For example, often times a router operates on one or more fields of apacket, especially the header, so the body of the packet is often storedin a separate memory while the packet header is manipulated, and basedon the results of the processing of the packet (i.e., the packet headerin this example), the entire packet is forwarded or dropped, etc.Additionally, these packets may contain one or more types ofinformation, including, but not limited to, voice, data, video, andaudio information. The term “item” is used generically herein to referto a packet or any other unit or piece of information or data, a device,component, element, or any other entity. The phrases “processing apacket” and “packet processing” typically refer to performing some stepsor actions based on the packet contents (e.g., packet header or otherfields), and such steps or action may or may not include modifying,storing, dropping, and/or forwarding the packet and/or associated data.

The term “system” is used generically herein to describe any number ofcomponents, elements, sub-systems, devices, packet switch elements,packet switches, routers, networks, computer and/or communicationdevices or mechanisms, or combinations of components thereof. The term“computer” is used generically herein to describe any number ofcomputers, including, but not limited to personal computers, embeddedprocessing elements and systems, control logic, ASICs, chips,workstations, mainframes, etc. The term “processing element” is usedgenerically herein to describe any type of processing mechanism ordevice, such as a processor, ASIC, field programmable gate array,computer, etc. The term “device” is used generically herein to describeany type of mechanism, including a computer or system or componentthereof. The terms “task” and “process” are used generically herein todescribe any type of running program, including, but not limited to acomputer process, task, thread, executing application, operating system,user process, device driver, native code, machine or other language,etc., and can be interactive and/or non-interactive, executing locallyand/or remotely, executing in foreground and/or background, executing inthe user and/or operating system address spaces, a routine of a libraryand/or standalone application, and is not limited to any particularmemory partitioning technique. The steps, connections, and processing ofsignals and information illustrated in the figures, including, but notlimited to any block and flow diagrams and message sequence charts, maybe performed in the same or in a different serial or parallel orderingand/or by different components and/or processes, threads, etc., and/orover different connections and be combined with other functions in otherembodiments in keeping within the scope and spirit of the invention.Furthermore, the term “identify” is used generically to describe anymanner or mechanism for directly or indirectly ascertaining something,which may include, but is not limited to receiving, retrieving frommemory, determining, defining, calculating, generating, etc.

Moreover, the terms “network” and “communications mechanism” are usedgenerically herein to describe one or more networks, communicationsmediums or communications systems, including, but not limited to theInternet, private or public telephone, cellular, wireless, satellite,cable, local area, metropolitan area and/or wide area networks, a cable,electrical connection, bus, etc., and internal communications mechanismssuch as message passing, interprocess communications, shared memory,etc. The term “message” is used generically herein to describe a pieceof information which may or may not be, but is typically communicatedvia one or more communication mechanisms of any type.

The term “storage mechanism” includes any type of memory, storage deviceor other mechanism for maintaining instructions or data in any format.“Computer-readable medium” is an extensible term including any memory,storage device, and/or storage mechanism. The term “memory” includes anyrandom access memory (RAM), read only memory (ROM), flash memory,integrated circuits, and/or other memory components or elements. Theterm “storage device” includes any solid state storage media, diskdrives, diskettes, networked services, tape drives, and other storagedevices. Memories and storage devices may store computer-executableinstructions to be executed by a processing element and/or controllogic, and data which is manipulated by a processing element and/orcontrol logic. The term “data structure” is an extensible term referringto any data element, variable, data structure, database, and/or one ormore organizational schemes that can be applied to data to facilitateinterpreting the data or performing operations on it, such as, but notlimited to memory locations or devices, sets, queues, trees, heaps,lists, linked lists, arrays, tables, pointers, etc. A data structure istypically maintained in a storage mechanism. The terms “pointer” and“link” are used generically herein to identify some mechanism forreferencing or identifying another element, component, or other entity,and these may include, but are not limited to a reference to a memory orother storage mechanism or location therein, an index in a datastructure, a value, etc. The term “associative memory” is an extensibleterm, and refers to all types of known or future developed associativememories, including, but not limited to binary and ternary contentaddressable memories, hash tables, TRIE and other data structures, etc.Additionally, the term “associative memory unit” may include, but is notlimited to one or more associative memory devices or parts thereof,including, but not limited to regions, segments, banks, pages, blocks,sets of entries, etc.

The term “one embodiment” is used herein to reference a particularembodiment, wherein each reference to “one embodiment” may refer to adifferent embodiment, and the use of the term repeatedly herein indescribing associated features, elements and/or limitations does notestablish a cumulative set of associated features, elements and/orlimitations that each and every embodiment must include, although anembodiment typically may include all these features, elements and/orlimitations. In addition, the phrase “means for xxx” typically includescomputer-readable medium containing computer-executable instructions forperforming xxx.

In addition, the terms “first,” “second,” etc. are typically used hereinto denote different units (e.g., a first element, a second element). Theuse of these terms herein does not necessarily connote an ordering suchas one unit or event occurring or coming before another, but ratherprovides a mechanism to distinguish between particular units.Additionally, the use of a singular tense of a noun is non-limiting,with its use typically including one or more of the particular thingrather than just one (e.g., the use of the word “memory” typicallyrefers to one or more memories without having to specify “memory ormemories,” or “one or more memories” or “at least one memory”, etc.).Moreover, the phrases “based on x” and “in response to x” are used toindicate a minimum set of items x from which something is derived orcaused, wherein “x” is extensible and does not necessarily describe acomplete list of items on which the operation is performed, etc.Additionally, the phrase “coupled to” is used to indicate some level ofdirect or indirect connection between two elements or devices, with thecoupling device or devices modifying or not modifying the coupled signalor communicated information. The term “subset” is used to indicate agroup of all or less than all of the elements of a set. The term“subtree” is used to indicate all or less than all of a tree. Moreover,the term “or” is used herein to identify a selection of one or more,including all, of the conjunctive items.

One embodiment identifies a particular item, and in response, generatesa locking request to an ordered lock. The ordered lock is configured tomaintain a locking queue of identifiers corresponding to lockingrequests in the order requested. One or more instructions are associatedwith the particular identifier, and when the particular identifierreaches the head of the locking queue, the one or more instructions areperformed.

In one embodiment, the instructions are associated with the particularidentifier in an operation performed subsequently to the lockingrequest. In one embodiment, the instructions are associated with theparticular identifier in an operation performed after another identifiercorresponding to a second locking request is added to the locking queue.In one embodiment, the locking queue contains multiple other identifierscorresponding to other items when the locking request for the particularitem is performed. In one embodiment, the one or more instructionsinclude a lock conversion instruction to associate the particular itemwith a second ordered lock. In one embodiment, the particular item is apacket. In one embodiment, the one or more instructions include a packetgather instruction. In one embodiment, one or more fields of theparticular packet are processed to identify a secondary ordered lock,and the one or more instructions include a lock conversion instructionto associate the particular item with a second ordered lock.

One embodiment repeatedly identifies a particular packet, and inresponse, generates a locking request to an ordered lock, wherein theordered lock maintains a locking queue of identifiers corresponding thelocking requests in the order requested. Acceptances requestscorresponding to packets are communicated to the ordered lock. Theordered lock repeatedly removes a particular identifier from the head ofthe locking queue, and grants a locking acceptance request correspondingto the particular identifier if a corresponding acceptance request waspreviously generated, or waits until the locking acceptance requestcorresponding to the particular identifier is generated and thengranting the locking acceptance request corresponding to the particularidentifier.

In one embodiment, the locking requests are non-blocking and acceptancerequests are blocking. In one embodiment, in response to granting thelocking acceptance request corresponding to a packet, the packet isforwarded. In one embodiment, in response to granting the lockingacceptance request corresponding to a packet, a second locking requestcorresponding to the packet to a particular secondary lock is made, withthe particular secondary lock being identified based on contents of thepacket.

One embodiment includes multiple packet processors, an ordered lockmanager, and a distributor. The ordered lock manager is configured toreceive lock requests, to receive instruction requests corresponding tothe lock requests, and to process instructions corresponding to the lockrequests in the order the lock requests are received and after animmediately prior lock request is released. The distributor isconfigured to receive a packet, make a locking request corresponding tothe packet to the ordered lock manager, and to distribute the packet toone or more processors. At least one of the one or more processors isconfigured to communicate a set of instructions corresponding to thepacket to the ordered lock manager.

In one embodiment, the set of instructions includes a packet gatherinstruction. In one embodiment, the set of instructions includes aninstruction for performing a lock release. In one embodiment, the set ofinstructions includes a convert instruction for performing a secondarylocking request.

One embodiment includes one or more locking mechanisms, multiple packetprocessors, and a packet distributor. The one or more locking mechanismsoperates multiple ordered locks, including a root ordered lock andmultiple secondary ordered locks. Each ordered lock including a queuefor storing locking items. Each locking mechanism is configured toreceive locking requests and to place indications of the lockingrequests in corresponding queues of the ordered locks, and to receiveand react to locking accepts and locking releases. The packetdistributor is configured to receive packets, to make root orderedlocking requests for each of the packets, and to distribute each of thepackets to the packet processors. Each packet processor is configured toreceive a particular packet, to accept a root ordered lock correspondingto the root ordered locking request for the particular packet, toprocess the packet to identify a secondary lock, to make a lockingrequest corresponding to the secondary lock, and to release the rootordered lock. In one embodiment, each packet processor is configured tomake the lock request corresponding to the secondary lock afteraccepting the root ordered lock corresponding to the root orderedlocking request for the particular packet and before releasing the rootordered lock.

FIG. 1A is a block diagram of an exemplary system employing oneembodiment. Shown is a packet switching system with packet processors101-102 and 104-105 interconnected by packet switch fabric 103. In oneembodiment, one or more of the packet processors 101-102 and 104-105uses ordered locking mechanisms to maintain required sequences ofpackets.

FIG. 1B is a block diagram of a system or component 120 thereof, suchas, but not limited to a packet processor, lock mechanism, lock manager,distributor, gatherer, or resource used in one embodiment. In oneembodiment, system or component 120 performs one or more processescorresponding to one of the flow diagrams illustrated or otherwisedescribed herein.

In one embodiment, component 120 includes a processing element 121,memory 122, storage devices 123, and an interface 124 for receiving andsending packets, items, and/or other information, which are typicallycoupled via one or more communications mechanisms 129 (shown as a busfor illustrative purposes.) Various embodiments of component 120 mayinclude more or less elements. The operation of component 120 istypically controlled by processing element 121 using memory 122 andstorage devices 123 to perform one or more scheduling tasks orprocesses. Memory 122 is one type of computer-readable medium, andtypically comprises random access memory (RAM), read only memory (ROM),flash memory, integrated circuits, and/or other memory components.Memory 122 typically stores computer-executable instructions to beexecuted by processing element 121 and/or data which is manipulated byprocessing element 121 for implementing functionality in accordance withthe invention. Storage devices 123 are another type of computer-readablemedium, and typically comprise solid state storage media, disk drives,diskettes, networked services, tape drives, and other storage devices.Storage devices 123 typically store computer-executable instructions tobe executed by processing element 121 and/or data which is manipulatedby processing element 121 for implementing functionality in accordancewith the invention.

Sequences of items may be maintained using ordered locks. These itemsmay correspond to anything, but using ordered locks to maintainsequences of packets may be particularly useful. One embodiment uses alocking request, acceptance, and release protocol. One embodimentassociates instructions with locking requests such that when a lock isacquired, the locking mechanism executes or causes to be executed theassociated instructions as an acceptance request of the lock is impliedby the association of instructions (or may be explicitly requested). Insome applications, the ordering of the entire sequence of packets is notrequired to be preserved, but rather only among certain sub-sequences ofthe entire sequence of items, which can be accomplished by converting aninitial root ordered lock (maintaining the sequence of the entire streamof items) to various other locks (each maintaining a sequence ofdifferent sub-streams of items).

One embodiment of a locking mechanism uses the following basic andextensible operations:

-   -   request(lock_id)—The context requests a lock. A “context”        typically refers to state and resources including processor        engine, thread, etc. associated with a packet or other entity        while it is being processed. If the requested lock is available        (i.e., no other context owns it) then a lock_grant is sent to        the requesting context. If however the lock is in possession of        another context, then the new request is queued until it moves        to the front of the queue and the lock_grant is sent. It is a        non-blocking operation, i.e., any code after the request but        before the accept is not part of the critical section, and can        be executed before the lock_grant is received.    -   accept(lock_id)—This is a blocking operation, which causes the        requesting context to block until it holds the desired lock        (i.e., lock_grant has been received). Any code executed after        the accept, but before the release is the critical section for        this lock.    -   release(lock_id)—This is the operation which releases the lock,        and makes it available for other requesting contexts.

FIGS. 2A-2C illustrate an ordered lock 200 used in one embodiment.Turning to FIG. 2A, lock mechanism 201 performs the locking operations,and can be implemented in an unlimited number of ways, including, butnot limited to a processing element and memory, discrete logic, a customASIC etc. In one embodiment, ordered lock 200 uses one or more lockingqueues 202 (or any other mechanism to maintain the order requests arereceived), typically one for each lock supported. In one embodiment,ordered lock 200 only services a single lock, and thus no lock ID isrequired to identify a particular lock (e.g., a root lock, a secondarylock, etc.) In one embodiment, ordered lock 200 services multiple locks,with the particular ordered lock typically being identified by a lock ID(e.g., a unique value, etc.) or via another mechanism. Lock requestqueues 202 can be implemented in an unlimited number of ways, such as indifferent memories, shift registers, a single memory with each queueelement identified using a link list or other data structure, etc.

FIG. 2B illustrates a lock mechanism process used in one embodiment forprocessing lock requests. Processing begins with process block 220. Asdetermined in process block 222, when a lock request is received orotherwise identified, then in process block 224, an identifiercorresponding to the identified lock request is placed at the end of thelock request queue corresponding to the request (e.g., that identifiedby a lock ID or other mechanism if more than one lock being supported bythe locking mechanism). Processing then returns to process block 222. Inthis manner, the order that locking requests are received is maintainedby the locking mechanism.

FIG. 2C illustrates a process used in one embodiment to process lockitems/requests for each queue supported by the locking mechanism.Processing begins at process block 240. As determined in process block242, when there is a lock identifier in the queue, then in process block244, the indication corresponding to a lock request at the head of thequeue is identified. As determined in process block 248, if an acceptrequest corresponding to the identifier has been received, then inprocess block 252, the accept request is granted. Processing then waitsat process block 254 until a corresponding release request is received,and then the indication is removed from the head of the queue in processblock 256, and processing returns to process block 242. Otherwise, asdetermined in process block 250, if a release request corresponding tothe identification is received, processing proceeds directly to processblock 256. Otherwise, processing returns to process block 248.

One embodiment of a locking mechanism uses the following basic andextensible operations:

-   -   request(lock_id)—The context requests a lock. If the requested        lock is available (i.e., no other context owns it) then a        lock_grant is sent to the requesting context. If however the        lock is in possession of another context, then the new request        is queued until it moves to the front of the queue and the        lock_grant is sent. It is a non-blocking operation, i.e., any        code after the request but before the accept is not part of the        critical section, and can be executed before the lock_grant is        received.    -   attach(operation+attributes, convert+dest_flow_id)—The attach        actually consists of an implied accept (i.e., get to the front        of the queue for the current flow_id), followed by do_action        and/or convert to a new flow_id and finally release current        lock. Embodiments may use different attach operations.

FIGS. 3A-3D illustrate an ordered lock 300 used in one embodiment.Turning to FIG. 3A, lock mechanism 301 performs the locking operations,and can be implemented in an unlimited number of ways, including, butnot limited to a processing element and memory, discrete logic, a customASIC etc. In one embodiment, ordered lock 300 uses one or more lockingqueues 302 (or any other mechanism to maintain the order requests arereceived), typically one for each lock supported. In one embodiment,ordered lock 300 only services a single lock, and thus no lock ID isrequired to identify a particular lock (e.g., a root lock, a secondarylock, etc.) In one embodiment, ordered lock 300 services multiple locks,with the particular ordered lock typically being identified by a lock ID(e.g., a unique value, etc.) or via another mechanism. Lock requestqueues 302 can be implemented in an unlimited number of ways, such asdifferent memories, shift registers, a single memory with each queueelement identified using a link list or other data structure, etc. Asillustrated, instructions 305 are associated with received lockrequests, such as those identified by lock identifiers stored in lockrequest queue(s) 302. These instructions can be associated with the lockrequests using an unlimited number of techniques, and these instructionscan be stored in queue 302 or in one or more other data structures.

FIG. 3B illustrates a lock mechanism process used in one embodiment forprocessing lock requests. Processing begins with process block 320. Asdetermined in process block 322, when a lock request is received orotherwise identified, then in process block 324, an identifiercorresponding to the identified lock request is placed at the end of thelock request queue corresponding to the request (e.g., that identifiedby a lock ID or other mechanism if more than one lock being supported bythe locking mechanism). Processing then returns to process block 322. Inthis manner, the order that locking requests are received is maintainedby the locking mechanism.

FIG. 3C illustrates a process used in one embodiment to processinstruction requests by a locking mechanism. Processing begins withprocess block 340. As determined in process block 342, when aninstruction request is identified (e.g., received, etc.), then inprocess block 344, these instructions are associated with the lockrequest (e.g., a lock identifier in a locking mechanism, or via anyother mechanism).

FIG. 3D illustrates a process used in one embodiment to process lockitems/requests for each queue supported by the locking mechanism.Processing begins at process block 360. As determined in process block362, when there is a lock identifier in the queue, then in process block364, the indication corresponding to a lock request at the head of thequeue is identified. Until instructions corresponding to the identifierhave been identified (e.g., received or otherwise identified now orpreviously), processing remains at 366. After corresponding instructionshave been identified, in process block 368, the instructions areperformed by the locking mechanism and/or another processing mechanism.

These instructions may be blocking (e.g., the lock must complete beforeproceeding to a next instruction or other operation) or non-blocking(e.g., initiate an operation and proceed with other instructions oroperations). In one embodiment, the performed instruction(s) may includeinitiating an operation and block until the operation is complete. Inone embodiment, the performed instruction(s) may include initiating anoperation and do not block until the operation is complete. In oneembodiment, the performed instruction(s) may include initiating anoperation and delay sending an acknowledgement indication to the lockrequestor until the operation is complete while proceeding with otherlock items in the queue. For example, an operation to gather parts of apacket from different memory locations and/or memories might beinitiated, while the acknowledgement operation might be delayed untilthe memory access or accesses have been completed so that the memorylocation(s) can be overwritten.

In process block 370, an acknowledgement message is sent to therequester, with this acknowledgment message being sent immediately ordelayed until some other operation is complete, and possibly proceedingwith processing more locking items in the queue before suchacknowledgement is sent. Processing returns to process block 362. Fromone perspective, the receipt of instructions acts as an implied lockacceptance request, or even in one embodiment, the acceptance is one ofthe instructions associated with a lock request or indication thereof.

FIGS. 4A-D illustrate the concept of a lock conversion used in oneembodiment. Note, the number and type of lock conversions used isextensible and may vary among embodiments to match the requirements ofthe application. Locks can be used to maintain strong ordering of astream of items. Additionally, locks can be used to induce ordering ofitems. For example, a lock can be converted to multiple different lockswhich allows the same order to be maintained within the different locks,while allowing the items of the different locks to be processed in anyorder, such as, but not limited to being processed in parallel.Similarly, multiple locks can be converted to a single lock whichinduces ordering among items previously in the different locks (e.g.,typically with the ordering being that in which locking requests areprocessed).

For example, packets arriving on an interface might each make a lockingrequest in the order they are received to a single root lock, or make alocking request to one of multiple root locks (e.g., one for eachreceiving port, protocol type, packet type, etc., or some combinationthereof). This maintains the order of the packets as the locks areprocessed in the order that the requests were made (e.g., the arrivalorder of packets in one embodiment). These locks can then be convertedto different locks based on the processing of the packet required orsome value included in the packet or other data structure, etc. Forexample, certain packet streams must maintain ordering. By convertingall locks corresponding to the packets of the stream from a root lock toa same other lock, this ordering is maintained. Similarly, this secondlock (or nth lock where n is any integer for that matter—as the numberof possible locking conversions is unbounded) may be converted toanother lock such as one corresponding to an output interface or port,and thus the original ordering can be maintained (even if lockconversions from other locks are made to the same lock as the relativeorder within each stream is maintained by the lock).

Turning first to FIG. 4A, illustrated is an example of an ordered lockconversion 400. A stream of items 401 is processed by a ordered lock 402(identified for simplicity as the “root lock”). When the root lock 402is acquired by a particular identifier/item, if it is associated with aflow (also referred to as a sub-sequence or sub-stream) within stream401, the ordered lock 404-406 corresponding to this flow is identifiedand a locking request is made to this secondary ordered lock 404-406.Note, ordered locks 402-406 can be implemented using one or more orderedlock mechanisms, with each lock implicitly identified or explicitlyidentified using a lock ID or other mechanism. Thus, the relevantordering within the initial stream as maintained by root ordered lock402 is transferred to each of the flow ordered locks 404-406, and thelock associated with an item is “converted” from root ordered lock 402to one or more of the flow ordered locks 404-406.

FIG. 4B illustrates such processing used by a locking mechanism in oneembodiment. Processing begins with process block 420, and proceeds toprocess block 422, wherein the acquired lock (e.g., indicationexplicitly or implicitly accepted at the front of the correspondingqueue or other ordering mechanism) in the root lock is identified. Note,processing may need to wait until a lock is acquired. Next, in processblock 424, a lock request is made in the flow ordered lock correspondingto the acquired lock. Processing then returns to process block 422.

Similarly, conversion of locks 440 can be made from multiple flow locks444-446 to another ordered lock 442 (identified for simplicity as the“root lock”) as illustrated in FIG. 4C to produce a stream of items 441.When one of the multiple flow locks 444-446 is acquired by a particularidentifier/item and a conversion operation is desired to root lock 442,a locking request is made to this secondary lock 442. Note, orderedlocks 442-446 can be implemented using one or more ordered lockmechanisms, with each lock implicitly identified or explicitlyidentified using a lock ID or other mechanism.

FIG. 4D illustrates such processing used by locking mechanisms in oneembodiment. Processing begins with process block 460, and proceeds toprocess block 462, wherein the acquired lock (e.g., indicationexplicitly or implicitly accepted at the front of the correspondingqueue or other ordering mechanism) in an ordered lock is identified.Note, processing may need to wait until a lock is acquired. Next, inprocess block 464, a lock request is made in an ordered lock. Processingthen returns to process block 462. Thus, when this process is performedin connection by multiple flow ordered locks to a single root flowordered lock, the original order of the items corresponding to themultiple flow ordered locks is maintained.

FIGS. 5A-D are a flow diagrams illustrating some of an unlimited numberof embodiments for using ordered locks to maintain sequences of packets.Turning first to FIG. 5A, processing begins with process block 500, andproceeds to process block 502, wherein a packet is received and acorresponding ordered lock request is made. Next, in process block 504,the packet is processed. In process block 506, an acceptance request ismade to the ordered lock. In process block 508, when the lock isacquired, the packet is further processed, dropped, sent etc., and thelock is released. By waiting until the lock is acquired, the originalordering is maintained. Processing of the flow diagram is complete asindicated by process block 510.

FIG. 5B illustrates a process used in one embodiment for processingpackets using ordered locking mechanisms. Processing begins with processblock 520, and proceeds to process block 522, wherein a packet isreceived and a corresponding ordered lock request is made. Next, inprocess block 524, a secondary flow associated with a packet isidentified. For example, an original stream of packets may be allpackets received on an interface, and a particular flow might beidentified based on a source address, destination address, protocoltype, quality of service requirement, group identification, and/or anyother information contained in a packet or external to a packet. In oneembodiment, all items belong to a secondary flow, which may include adefault flow for packets not associated with another particular flow. Inone embodiment, only some of the items belong to a secondary flow, andtypically those packets not belonging to a secondary flow are allowed toproceed as processed.

In process block 526, an acceptance request to the root ordered lock,and typically the processing of the packet continues. In process block528, when the lock is acquired, a lock request is made to the secondaryordered lock corresponding to the identified secondary flow. In processblock 530, when processing of the packet is finished, an acceptancerequest is made to the corresponding secondary ordered lock, and inprocess block 532, when the secondary ordered lock is acquired, thepacket is further processed, dropped, sent etc., and the lock isreleased. Processing of the flow diagram is complete as indicated byprocess block 534.

Processing of the flow diagram of FIG. SC begins with process block 560,and proceeds to process block 562, wherein a packet is received and acorresponding ordered lock request is made. Next, in process block 564,the packet is processed. In process block 566, when processing of thepacket is complete, a set of one or more instructions is associated withthe lock request. Note, the atomic operations to be performed inresponse to the instructions is extensible, and is typically defined inaccordance with the needs of the application. For example, these atomicoperations may include an operation including, but not limited toconversion of locks, sequence number generation and/or checking, errorchecking and/or correcting, memory operations, data manipulationoperations, initiating another operation, etc. In process block 568,when the lock is acquired, the instructions are executed by the lockmechanism or another mechanism, typically to further process, drop orgather/send packet, convert the root lock request, etc., and the lock isreleased. By waiting until the lock is acquired before executing theinstructions, the original ordering is maintained. Processing of theflow diagram is complete as indicated by process block 570.

FIG. 5D illustrates a process used in one embodiment for processingpackets using ordered locking mechanisms. Processing begins with processblock 580, and proceeds to process block 582, wherein a packet isreceived and a corresponding root ordered lock request is made. Next, inprocess block 584, a secondary flow associated with a packet isidentified. In process block 586, when processing of the packet iscomplete, a set of one or more instructions is associated with the lockrequest, with these instructions including a convert operationinstruction. In process block 588, when the lock is acquired, theinstructions are executed by the lock mechanism or another mechanism, toconvert the root lock to the identified secondary lock. In process block590, when processing of the packet is complete, a set of one or moreinstructions is associated with the secondary lock request. In processblock 592, when the lock is acquired, the instructions are executed bythe lock mechanism or another mechanism, typically to further process,drop or gather/send packet, convert the root lock request, etc., and thelock is released. Processing of the flow diagram is complete asindicated by process block 594.

FIG. 6A is a block diagram of an exemplary system using ordered locks tomaintain sequences of packets. Packets 601 are received by packetprocessor 600 and typically stored in packet memory 604 via multiplexor602 (as packet processor allows for recirculation of packets fromcomponent 624). Distributor 606 is responsible for assigning a packet toone or more of the packet processing engines 610 for performing theactual packet processing. This processing may use cache 612, DRAMcontrols 614 and external memory 615, lookup control 616, associativememory control 618 and associative memory 619, and/or other componentswhich are typically accessed via coupled resource network 608.Distributor 606 also notifies lock manager and resequencer 620 of theassignment of the packet, and a root lock request is made. Packetprocessing engines 610 perform lock requests, acceptances, releases,attaching/associating instructions with lock requests in conjunctionwith lock manager and resequencer 620. At the appropriate time, gathermechanism 622 is notified that a packet should be gathered and sent, forexample based on a gather instruction associated with a lock request. Agather instruction typically defines how to accumulate or gatherportions of a processed packet in order to form the processed packet,and may included the semantics to send the packet. Gathered packets arecommunicated to buffer, queue, scheduler, memory control component 624to send the processed packet as indicated by packets 629.

The operation of one embodiment of packet processor 600 and/or otherpacket processors is described in relation to FIG. 6B. Processing ofwhich begins with process block 640, and proceeds to process block 642,wherein a packet is received and stored in packet memory, and thedistributor is informed of the arrival and location of the packet. Inprocess block 644, the distributor identifies to which packet processingengine and possibly thread to assign to process the packet. In processblock 646, the distributor notifies the packet processing engine of theassignment and makes a root locking request corresponding to thereceived stream to which the packet belongs, such as the interface onwhich it was received. In one embodiment, the stream is identified basedon the packet contents, but other embodiments minimize the processing ofthe packet performed by the distributor. The distributor also makes alocking request on behalf of the assigned packet processing engine tothe lock manager for the packet. In process block 648, the assignedpacket processing engine retrieves the relevant portion (e.g., headerand possibly other fields) of the packet from the packet memory, andprocesses this and/or other information to identify a secondaryflow/lock, if any, to which the packet is associated and continuesprocessing the packet.

As determined in process block 650, if a convert operation is to beperformed, then in process block 652, the packet processing engineassociates/attaches a convert instruction to the root lock request, andwhen the root lock is acquired, such as the corresponding identifierreaches the front of the root lock queue, the lock manager performs (orcauses another mechanism to perform) instructions to convert the lockand then releases the root lock.

Next, in process block 654, when processing of the packet is complete,the packet processing engine attaches a gather instruction to thesecondary or root lock request (depending on whether an ordered lockconversion operation was performed). When this lock is acquired, thelock manager performs (or causes another mechanism to perform)instructions to gather the fields of the packet to form the packet to besent, and forwards the packet. Processing of the flow diagram iscomplete as indicated by process block 656.

In view of the many possible embodiments to which the principles of ourinvention may be applied, it will be appreciated that the embodimentsand aspects thereof described herein with respect to thedrawings/figures are only illustrative and should not be taken aslimiting the scope of the invention. For example and as would beapparent to one skilled in the art, many of the process block operationscan be re-ordered to be performed before, after, or substantiallyconcurrent with other operations. Also, many different forms of datastructures could be used in various embodiments. The invention asdescribed herein contemplates all such embodiments as may come withinthe scope of the following claims and equivalents thereof.

1. A method for maintaining ordering, the method comprising: employing aparticular machine to perform the following steps: identifying aparticular item of a plurality of items and in response, generating alocking request to an ordered lock corresponding to the particular item,wherein the ordered lock is configured to maintain a locking queue ofidentifiers corresponding to locking requests in the order requested andto place a particular identifier corresponding to the locking request atthe end of the locking queue; associating one or more instructions withthe particular identifier corresponding to the locking request; andidentifying the particular identifier at the head of the locking queue,and in response, performing said one or more instructions.
 2. The methodof claim 1, wherein said associating one or more instructions with theparticular identifier is performed after another identifiercorresponding to a second locking request is added to the locking queue.3. The method of claim 1, wherein the locking queue contains a pluralityof other identifiers corresponding to other items when said generatingthe locking request to the ordered lock is performed.
 4. The method ofclaim 1, wherein said one or more instructions includes a lockconversion instruction to associate the particular item with a secondordered lock.
 5. The method of claim 1, wherein each item of theplurality of items includes a packet.
 6. The method of claim 5, whereinsaid one or more instructions includes a packet gather instruction. 7.The method of claim 5, comprising processing one or more fields of theparticular packet to identify a secondary ordered lock; and wherein saidone or more instructions includes a lock conversion instruction toassociate the particular item with a second ordered lock.
 8. The methodof claim 1, including sending a release lock acknowledgement message;wherein said one or more instructions includes initiating an operation;and wherein said sending the release lock acknowledgement message isperformed after performance of the operation is complete.
 9. The methodof claim 1, including sending a release lock acknowledgement message;wherein said one or more instructions includes initiating an operation;and wherein said sending the release lock acknowledgement message isperformed before performance of the operation is complete.
 10. A methodfor maintaining packet ordering, the method comprising: employing aparticular machine to perform the following steps: repeatedlyidentifying a particular packet of a plurality of packets and inresponse, generating a locking request to an ordered lock correspondingto the particular packet, wherein the ordered lock maintains a lockingqueue of identifiers corresponding to the locking requests in the orderrequested; communicating acceptance requests corresponding to packets ofthe plurality of packets to the ordered lock; and repeatedly removing aparticular identifier from the head of the locking queue, and granting alocking acceptance request corresponding to the particular identifier ifa corresponding said acceptance request was previously generated, orwaiting until the locking acceptance request corresponding to theparticular identifier is generated and then granting the lockingacceptance request corresponding to the particular identifier.
 11. Themethod of claim 10, wherein said locking requests are non-blocking andsaid acceptance requests are blocking.
 12. The method of claim 10,comprising: in response to said granting the locking acceptance requestcorresponding to a packet, forwarding the packet.
 13. The method ofclaim 10, comprising: in response to said granting the lockingacceptance request corresponding to a packet, making a second lockingrequest corresponding to the packet to a particular secondary lock of aplurality of secondary ordered locks, the particular secondary lockbeing identified based on contents of the packet.
 14. The method ofclaim 10, wherein the locking request corresponding to a first packet ofthe plurality of packets is generated before the locking requestcorresponding to the second packet of the plurality of packets, and theacceptance request corresponding to the second packet is made before theacceptance request corresponding to the first packet, and the acceptancerequest corresponding to the first packet is granted before theacceptance request corresponding to the second packet.
 15. An apparatusfor processing packets, the apparatus comprising: a plurality of packetprocessors; an ordered lock manager configured to receive lock requests,to receive instruction requests corresponding to said lock requests, andto process instructions corresponding to said lock requests in the ordersaid lock requests are received; wherein said instructions of eachparticular lock request are said processed after a lock request of saidlock requests, immediately prior to said particular lock request in theorder said lock requests are said received, is released; and adistributor, coupled to the plurality of packet processors and theordered lock manager, configured to receive a packet, make a lockingrequest corresponding to the packet to the ordered lock manager, and todistribute the packet to one or more processors of the plurality ofpacket processors; wherein at least one of said one or more processorsis configured to communicate a set of instructions corresponding to thepacket to the ordered lock manager.
 16. The apparatus of claim 15,wherein the set of instructions includes a packet gather instruction.17. The apparatus of claim 16, wherein the set of instructions includesan instruction for performing a lock release.
 18. The apparatus of claim15, wherein the set of instructions includes a convert instruction forperforming a secondary locking request.
 19. The apparatus of claim 15,wherein the set of instructions includes an instruction for performing alock release request.
 20. An apparatus for processing packets, theapparatus comprising: one or more locking mechanisms for operating aplurality of ordered locks, each ordered lock of the plurality ofordered locks including a queue for storing locking items, each lockingmechanism of said one or more locking mechanisms configured to receivelocking requests and to place indications of the locking requests incorresponding queues of said plurality of ordered locks, and to receiveand react to locking accepts and locking releases, the plurality ofordered locks including a root ordered lock and a secondary orderedlock; a plurality of packet processors; a packet distributor configuredto receive packets, to make root ordered locking requests for each ofsaid packets, and to distribute each of said packets to the plurality ofpacket processors; each packet processor of the plurality of packetprocessors configured to receive a particular packet, to accept a rootordered lock corresponding to the root ordered locking request for theparticular packet, to process the packet to identify a secondary lock,to make a locking request corresponding to the secondary ordered lock,and to release the root ordered lock.
 21. The apparatus of claim 20,wherein said each packet processor is configured to perform said makethe lock request corresponding to the secondary lock after saidaccepting the root ordered lock corresponding to the root orderedlocking request for the particular packet and before said releasing theroot ordered lock.
 22. An apparatus for maintaining ordering, theapparatus comprising: means for identifying a particular item of aplurality of items and in response generating a locking request to anordered lock corresponding to the particular item, wherein the orderedlock is configured to maintain a locking queue of identifierscorresponding to locking requests in the order requested and to place aparticular identifier corresponding to the locking request at the end ofthe locking queue; means for associating one or more instructions withthe particular identifier corresponding to the locking request; andmeans for identifying the particular identifier at the head of thelocking queue and in response performing said one or more instructions.23. The apparatus of claim 22, wherein said means for associating one ormore instructions with the particular identifier corresponding to thelocking request is configured to associate one or more instructions withthe particular identifier after another identifier corresponding to asecond locking request is added to the locking queue.
 24. The apparatusof claim 22, wherein said one or more instructions includes a lockconversion instruction to associate the particular item with a secondordered lock.
 25. The apparatus of claim 22, wherein each item of theplurality of items includes a packet.
 26. The apparatus of claim 25,wherein said one or more instructions includes a packet gatherinstruction.
 27. The apparatus of claim 25, comprising means forprocessing one or more fields of the particular packet to identify asecondary ordered lock; and wherein said one or more instructionsincludes a lock conversion instruction to associate the particular itemwith a second ordered lock.
 28. An apparatus for maintaining packetordering, the apparatus comprising: means for repeatedly identifying aparticular packet of a plurality of packets and in response, generatinga locking request to an ordered lock corresponding to the particularpacket, wherein the ordered lock maintains a locking queue ofidentifiers corresponding to the locking requests in the orderrequested; means for communicating acceptance requests corresponding topackets of the plurality of packets to the ordered lock; and means forrepeatedly removing a particular identifier from the head of the lockingqueue, and granting a locking acceptance request corresponding to theparticular identifier if a corresponding said acceptance request waspreviously generated, or waiting until the locking acceptance requestcorresponding to the particular identifier is generated and thengranting the locking acceptance request corresponding to the particularidentifier.
 29. The apparatus of claim 28, wherein said locking requestsare non-blocking and said acceptance requests are blocking.
 30. Theapparatus of claim 28, comprising: means for forwarding the packet inresponse to said granting the locking acceptance request correspondingto a packet.
 31. The apparatus of claim 28, comprising: means for makinga second locking request corresponding to the packet to a particularsecondary lock of a plurality of secondary ordered locks in response tosaid granting the locking acceptance request corresponding to a packet;and means for identifying the particular secondary lock based oncontents of the packet.
 32. The apparatus of claim 28, wherein thelocking request corresponding to a first packet of the plurality ofpackets is generated before the locking request corresponding to thesecond packet of the plurality of packets; and the acceptance requestcorresponding to the second packet is made before the acceptance requestcorresponding to the first packet; and the acceptance requestcorresponding to the first packet is granted before the acceptancerequest corresponding to the second packet.
 33. A tangiblecomputer-readable medium containing computer-executable instructions forperforming steps for maintaining ordering, said steps comprising:identifying a particular item of a plurality of items and in response,generating a locking request to an ordered lock corresponding to theparticular item, wherein the ordered lock is configured to maintain alocking queue of identifiers corresponding to locking requests in theorder requested and to place a particular identifier corresponding tothe locking request at the end of the locking queue; associating one ormore instructions with the particular identifier corresponding to thelocking request; and identifying the particular identifier at the headof the locking queue, and in response, performing said one or moreinstructions.
 34. The computer-readable medium of claim 33, wherein saidassociating one or more instructions with the particular identifier isperformed after another identifier corresponding to a second lockingrequest is added to the locking queue.
 35. The computer-readable mediumof claim 33, wherein the locking queue contains a plurality of otheridentifiers corresponding to other items when said generating thelocking request to the ordered lock is performed.
 36. Thecomputer-readable medium of claim 33, wherein said one or moreinstructions includes a lock conversion instruction to associate theparticular item with a second ordered lock.
 37. The computer-readablemedium of claim 33, wherein each item of the plurality of items includesa packet.
 38. The computer-readable medium of claim 37, wherein said oneor more instructions includes a packet gather instruction.
 39. Thecomputer-readable medium of claim 37, wherein said steps includeprocessing one or more fields of the particular packet to identify asecondary ordered lock; and wherein said one or more instructionsincludes a lock conversion instruction to associate the particular itemwith a second ordered lock.
 40. A tangible computer-readable mediumcontaining computer-executable instructions for performing steps formaintaining packet ordering, said steps comprising: repeatedlyidentifying a particular packet of a plurality of packets and inresponse, generating a locking request to an ordered lock correspondingto the particular packet, wherein the ordered lock maintains a lockingqueue of identifiers corresponding the locking requests in the orderrequested; communicating acceptance requests corresponding to packets ofthe plurality of packets to the ordered lock; and repeatedly removing aparticular identifier from the head of the locking queue, and granting alocking acceptance request corresponding to the particular identifier ifa corresponding said acceptance request was previously generated, orwaiting until the locking acceptance request corresponding to theparticular identifier is generated and then granting the lockingacceptance request corresponding to the particular identifier.
 41. Thecomputer-readable medium of claim 40, wherein said locking requests arenon-blocking and said acceptance requests are blocking.
 42. Thecomputer-readable medium of claim 40, wherein said steps include: inresponse to said granting the locking acceptance request correspondingto a packet, forwarding the packet.
 43. The computer-readable medium ofclaim 40, wherein said steps include: in response to said granting thelocking acceptance request corresponding to a packet, making a secondlocking request corresponding to the packet to a particular secondarylock of a plurality of secondary ordered locks, the particular secondarylock being identified based on contents of the packet.
 44. Thecomputer-readable medium of claim 40, wherein the locking requestcorresponding to a first packet of the plurality of packets is generatedbefore the locking request corresponding to the second packet of theplurality of packets, and the acceptance request corresponding to thesecond packet is made before the acceptance request corresponding to thefirst packet, and the acceptance request corresponding to the firstpacket is granted before the acceptance request corresponding to thesecond packet.
 45. The computer-readable medium of claim 40, whereinsaid one or more instructions includes initiating an operation; andwherein said steps include sending a release lock acknowledgementmessage after performance of the operation is complete.
 46. Thecomputer-readable medium of claim 40, wherein said one or moreinstructions includes initiating an operation; and wherein said stepsinclude sending a release lock acknowledgement message beforeperformance of the operation is complete.
 47. An apparatus forprocessing packets, the apparatus comprising: a plurality of packetprocessors; an ordered lock manager configured to receive lock requests,to receive instruction requests corresponding to said lock requests, andto process instructions corresponding to said lock requests in the ordersaid lock requests are received; and a distributor, coupled to theplurality of packet processors and the ordered lock manager, configuredto receive a packet, make a locking request corresponding to the packetto the ordered lock manager, and to distribute the packet to one or moreprocessors of the plurality of packet processors; wherein at least oneof said one or more processors is configured to communicate a set ofinstructions corresponding to the packet to the ordered lock manager.48. The apparatus of claim 47, wherein the set of instructions includesa packet gather instruction.
 49. The apparatus of claim 48, wherein theset of instructions includes an instruction for performing a lockrelease.
 50. The apparatus of claim 47, wherein the set of instructionsincludes a convert instruction for performing a secondary lockingrequest.
 51. The apparatus of claim 47, wherein the set of instructionsincludes an instruction for performing a lock release request.